1) Behcet disease is a disease which produces 4 main symptoms of recurrent aphthous ulcers on the oral mucous mucosa, skin lesions, eye lesions, and genital ulcers. This is also an intractable disease of unknown cause which presents systemic organ damages in the central nervous system/meninges,arteries/veins, articulations, and gastrointestinal tracts.
2) Behcet disease which is mainly located in the intestinal tract is called intestinal Behcet's disease, and it presents charateristic pathognomonic findings in the ileocecum.
<Major symptoms>
-Recurrent aphthous ulcers on the oral mucosa: They are symptoms seen in almost all patients, painful round sharply-circumscribed shallow ulcers of several mm -several cm in diameter, and develop commonly in the oral mucosa like the lips, gum, and buccal regions. In Behcet disease, they can be earliest symptoms and repeat recurrence and cure.
-Skin lesions: Erythema nodosum, Subcutaneous thrombophlebitis, and Folliculitis are major symptoms.　Many erythema nodosums develop on the extensor side of the lower leg, and especially on the thigh, upper limb and others. They are circular of 1-3mm in diameter, and painful subcutaneous induration. Its surfaces have poorly-defined erythemas, and are associated with slight protuberances.　Histogenetically neutrophilic infiltration of subcutaneous fatty tissues is recognized in the deep layer of the cutis.
-Eye lesions: Recurrent hypopyon uveitis is main.

Criteria
1. Major symptoms
1) Recurrent aphthous ulceration of the oral mucosa
2) Skin Lesions
a. Erythema nodosum
b. Subcutaneous thrombophlebitis
c. Folliculitis-like erruptions Reference findings: cutaneous hyperirritability
3) Eye Lesions
a. Iridocyclitis
b. Retino-uveitis (chorioretinitis)
c. If following observations are recognized they come into compliance with the standard of a.b.
They are Posterior synechia of the iris, lens pigmentation, choroidal atrophy, neural atrophy, complicated cataract, secondary glaucoma, and phthisis of eyeball which are thought to pass through a.b.
4) Genital ulcers
2. Minor symptoms
1) Arthris without deformity and ankylosis
2) Epididymitis
3) Gastrointestinal lesions characterized by ileocecal ulcers
4) Vascular lesions
5) Moderate or more serious degree of central nervous system symptoms
3. Criteria of Diagnosis for disease type
1) Complete
4 major symptoms appear in the course
2) Incomplete
a. 3 symptoms, or 2 symptoms and 2 minor symptoms appear in the course
b. Typical ocular symptoms and another 1 symptom, or 2 minor symptoms appear in the course
3) Suspected
Though a part of major symptoms appear, it does not meet conditions of Incomplete type, and typical minor symptoms repeat or exacerbate
4) Specific lesions
a. Intestinal Behcet's disease
b. Vascular Behcet's disease
c. Neuro-Behcet's disease